These studies are concerned with the relationship between the immune and endocrine systems and the role of milk in development of immunocompetence. Primary attention will be focused on: a. Effect of milk on thymus-dependent immunocompetence measured by mitogen-induced blastogenesis. b. Endocrine influences on cyclic nucleotide metabolishm of thymus cells during leukemogenesis and, c. Studies of association between human endocrine disease and histocompatibility markers and immunocompetence. BIBLIOGRAPHIC REFERENCES: Robert G. Kemp, Pei-Yung Shu, & Rene J. Duquesnoy: Changes in Lymphoid Cyclic Adenosine 3':5': - Monophosphate Metabolism during Murine Leukemogenesis. Cancer Research. 35:2440-2445, 1975.